Disposable absorbent devices for the absorption of human exudates are widely used. These disposable devices typically have a compressed mass of absorbent formed into the desired shape, which is typically dictated by the intended consumer use. In the area of a menstrual tampon, the device is intended to be inserted in a body cavity for absorption of the body fluids generally discharged during a woman's menstrual period.
There exists in the female body a complex process which maintains the vagina and physiologically related areas in a healthy state. In a female between the age of menarche and menopause, the normal vagina provides an ecosystem for a variety of microorganisms. Bacteria are the predominant type of microorganism present in the vagina; most women harbor about 10.sup.9 bacteria per gram of vaginal exudate. The bacterial flora of the vagina is comprised of both aerobic and anaerobic bacteria. The more commonly isolated bacteria are Lactobacillus species, corynebacteria, Gardnerella vaginalis, Staphylococcus species, Peptococcus species, aerobic and anaerobic Streptococcal species, and Bacteroides species. Other microorganisms that have been isolated from the vagina on occasion include yeast (Candida albicans), protozoa (Trichomonas vaginalis), mycoplasma (Mycoplasma hominis), chlamydia (Chlamydia trachomatis), and viruses (Herpes simplex). These latter organisms are generally associated with vaginitis or venereal disease, although they may be present in low numbers without causing symptoms.
Physiological, social and idiosyncratic factors affect the quantity and species of bacteria present in the vagina. Physiological factors include age, days of the menstrual cycle, and pregnancy. For example, vaginal flora present in the vagina throughout the menstrual cycle can include lactobacilli, corynebacterium, ureaplasma, and mycoplasma. Social and idiosyncratic factors include method of birth control, sexual practices, systemic disease (e.g. diabetes), and medication.
Bacterial proteins and metabolic products produced in the vagina can affect other microorganisms and the human host. For example, the vagina between menstrual periods is mildly acidic having a pH ranging from about 3.8 to about 4.5. This pH range is generally considered the most favorable condition for the maintenance of normal flora. At that pH, the vagina normally harbors the numerous species of microorganisms in a balanced ecology, playing a beneficial role in providing protection and resistance to infection and makes the vagina inhospitable to some species of bacteria such as Staphylococcus aureus (S. aureus). The low pH is a consequence of the growth of lactobacilli and their production of acidic products. Microorganisms in the vagina can also produce antimicrobial compounds such as hydrogen peroxide and bactericides directed at other bacterial species. One example is the lactocins, bacteriocin-like products of lactobacilli directed against other species of lactobacilli.
Some microbial products may affect the human host. For example, S. aureus can produce and excrete into its environment a variety of exoproteins including enterotoxins, Toxic Shock Syndrome Toxin-1 (TSST-1), and enzymes such as proteases and lipase.
S. aureus is found in the vagina of approximately 16% of healthy women of menstrual age. Approximately 25% of the S. aureus isolated from the vagina are capable of producing TSST-1. TSST-1 and some of the staphylococcal enterotoxins have been identified as causing Toxic Shock Syndrome (TSS) in humans.
Symptoms of TSS generally include fever, diarrhea, vomiting and a rash followed by a rapid drop in blood pressure. Systemic vital organ failure occurs in approximately 6% of those who contact the disease. S. aureus does not initiate TSS as a result of the invasion of the microorganism into the vaginal cavity. Instead as S. aureus grows and multiplies, it can produce Toxic Shock Syndrome Toxin 1 (TSST-1; synonyms: pyrogenic exotoxin C and enterotoxin F). Only after entering the bloodstream does the TSST-1 toxin act systemically and produce the symptoms attributed to Toxic Shock Syndrome.
Menstrual fluid has a pH of approximately 7.3. During menses, the pH of the vagina moves toward neutral and can become slightly alkaline. This change permits microorganisms whose growth is inhibited by an acidic environment the opportunity to proliferate. For example, S. aureus is more frequently isolated from vaginal swabs during menstruation than from swabs collected between menstrual periods.
There have been numerous attempts to reduce or eliminate pathogenic microorganisms and menstrually occurring TSS by incorporating into a tampon pledget one or more biostatic, biocidial, and/or detoxifying compounds. For example, L-ascorbic acid has been applied to a menstrual tampon to detoxify toxin found in the vagina of the human female during menstruation.
Incorporating glyceryl triacetate into a tampon pledget has been suggested. Glyceryl triacetate is readily broken down into glycerol and acetic acid by the enzymatic action of esterase. Esterase is present in the vaginal epithelium and in menstrual fluid. The enzymatic action of the esterase is in turn controlled by the pH of the environment, being more active when the pH is on the alkaline side. Since the pH of the vagina moves toward the alkaline side during menstruation, the enzymatic activity of the esterase automatically increases and attacks the glyceryl triacetate. This releases acetic acid rapidly, which has the potential to reduce the pH and enzymatic activity of the esterase. However, menstrual fluid is well buffered and the acetic acid is ineffective at lowering the pH of the menstrual fluid.
Others have incorporated monoesters and diesters of polyhydric aliphatic alcohols and a fatty acid containing from 8 to 18 carbon atoms. For example, glycerol monolaurate (GML) has been used to inhibit the production of S. aureus enterotoxins and TSST-1. However, as noted above, esterase is abundantly present in the vaginal epithelium and menstrual fluid. This esterase, in combination with esterase and lipase produced by bacteria can enzymatically degrade the esters into non-effective compounds. Until now, persons skilled in the art have not appreciated the affects of lipase and esterase on ester compounds. Thus, one or more ester compounds may have to be added to the absorbent article, such as a tampon pledget, in sufficiently high concentrations to detrimentally effect the normal flora present in the vaginal area. When the natural condition is altered, overgrowth by pathogen(s) may take place resulting in a condition known as vaginitis.
Accordingly, there exists a need for an absorbent product that has incorporated therein a compound that will: effectively inhibit the production of exoproteins, such as TSST-1, from Gram positive bacterium; will be substantially unaffected by the enzymes lipase and esterase; and will not substantially alter the natural flora found in the vaginal area.